Kazumasa Ozawa

SELF-COMPACTING HIGH PERFORMANCE CONCRETE

A self-compacting high-performance concrete has been developed, which is not affected by workmanship during placing and needs no subsequent consolidation. Self-compacting concrete can lead to innovative construction systems, save labour, and eliminate consolidation noise. It has been used in Japan for bridge girders, towers, and piers, and for other structures. It is being used in the manufacture of precast concrete, where it eliminates the need for vibrating machines and their noise. Requirements for self-compactibility vary according to the structure to be built. Self-compacting concrete needs high deformability without separation of materials. To increase its deformability, its water-powder ratio should be increased, or a superplasticiser should be added. Its coarse aggregate content should be limited. As long as a reliable supply of ready-mixed concrete is available, a mix design for general-purpose self-compacting high-performance concrete is available. Self-compacting concrete has minimal bleeding. Its strength is determined by the properties of the binder and the water-cement or water-binder ratio, as for ordinary concrete.

Self-Compactable High-Performance Concrete in Japan

Self-compactable high performance concrete requiring no consolidation in situ has been recently developed in Japan to improve the reliability of concrete and concrete structures. This concrete is a significant material innovation for a new generation of concrete structures. A review of the concrete and the applications are described.

Farmers' Access to Resources via Networks in Remote Rural Areas with Mobile Phone Reception: Creating a Resource Battery for a Mountain Tribe in South India

Abstract Inhabitants of the most remote areas tend to have low access to information and resources potentially contributing to well-being. Ongoing expansion of ICTs deeper into rural areas is expected to improve this situation by enabling them to contact geographically distant others. We interviewed 79 women and men in an indigenous tribe in the mountains of Tamil Nadu, India, where explosively expanding mobile phone signal entered prior to other types of infrastructure, and we inductively developed a scale for assessment of the inhabitants’ overall access to valued resources through their personal networks. It was found that the mobiles contributed primarily to the maintenance of existing networks and to speedier mobilization of already accessible resources. However, since the phone owners called only with people whom they already knew well, they did not expand their networks nor increased their overall access resources.

Stock Management of Civil Engineering Infrastructure in Asia

Infrastructure development, which can help distribute resources and serve as a base of service delivery, is indispensable to the welfare of human society and development. The quality and efficiency of infrastructure have a great influence on the quality of life of the people, social soundness, and economic activity. The Romans, for example, developed an extensive road network, built aqueducts and bridges, and thus helped cement their empire. The provision of infrastructure supported the economic development of every country in the world, and superior infrastructure systems have contributed greatly to an improvement in the overall quality of life. This paper is designed to introduce some views on infrastructure management and stock management in the countries of Asia. It focuses on management aspects of the civil engineering infrastructure, i.e. it excludes buildings. Figure 1-1 shows the economic development in Asian countries (the gross national income per capita from 1960 to the present). Compared to Southeast Asia and South Central Asia, East Asia has experienced a far faster economic growth over this period. Infrastructure is indispensable to the welfare of human society as well as economic development. The transition of social capital stock in Japan, based on the data from the Cabinet Office is described in Fig. 1-2. In 1998, it was valued at more than 600 trillion yen. The major parts of it are in the categories of “Road” and “Mountain/River Improvement.” Economic development in Japan has also been supported by integrated infrastructure development.

Practice and Effect of Case Method using Audio-visual Case

The Case Method is said to be one of the most effective way to acquire a practicalcapability. Using actual “case” happened before, participants discuss about the problem occurred in the story. Using audio-visual case, several case discussions were held. Through these discussions, new method of knowledge transfer was found. When experienced and few experienced managers make a discussion together, specific management skills can be revealed from experienced managers and non-skilled engineers can acquire these skills. As a tool to extract specific skills from experienced managers, audio-visual case is very effective, because audio-visual case can provide specific examples of management problems simultaneously to participants who watch case and they could consider these problems at the same time. And many techniques of discussion coordinator were found through observing professional discussion coordinators. These techniques are found to be useful to make case discussion more effective.

ENHANCEMENT ON DURABILITY OF CONCRETE STRUCTURES BY PREVENTING CRACKS DUE TO SETTLEMENT

In reinforced concrete structures the surface layer has an important role to prevent external attacks which can make causes for corrosion of reinforcing bars. For realizing dense and non-porous concrete on unformed surfaces a surface tamping vibrator has been developed and applied in practical construction procedures. Effects of the equipment has also been verified by some experimental works with checking a ratio of flexunal strength of specimen between with and without tamping procedures. According to the practical and experimental results standard usages of the surface tamping vibrator is proposed for surface finishing to enhance durability of concrete structures.